Marine litter and plastic litter in particular, represent a significant potential risk for marine ecosystems. In the marine realm, plastic litter distribution depends mostly on its different sources, from municipal waste-water effluents, to cosmetic products, agriculture and many other human activities.

This study aimed to define levels and principal features of marine litter (plastic litter in particular) in shallow coastal sediments collected around the Silba and Grebena Islands affected by different levels of human pressure (high impacted, low impacted, and marine protected area, MPA).

The results show that while macroplastics were in general absent, plastic litter was characterized by the dominance of microplastics in both islands; fibers representing, on average, the principal shape recorded. While differences on the plastic litter composition were found in relation to the different levels of human stress, microplastics were present in all sites.

It is stressed that marine litter and, in particular, plastics are pollutants that cannot be effectively faced by MPAs due to inputs coming from far sources. It is underlined that, as the removal of microplastics from contaminated marine sediments is actually impossible, prevention is the only weapon available to reduce microplastic levels in sediments in the near future.

Renzi et al. (2019) Marine litter in sediments related to ecological features in impacted sites and marine protected areas (Croatia). Marine Pollution Bulletin 138:25-29.